Tractor Repair: grinding gear, shaft bearing, clutch pedal

Question
Hello, I have a case 485 1988 and it has just started making a grinding noise when I try to change the gear range. It has low, high and reverse on one selector and then 4 speed on the other. I do not have any problems shifting gears even on the run but when I go from neutral to any of the high, low or reverse it seems like the clutch is not completely disengaged. The gears will then make a grinding noise before engaging and I also noticed that the tractor seems to want to creep forward (or reverse if reverse is selected). The clutch grabs quite high when the pedal is lifted, the pedal can be slightly lifted. It does not slip. I tried to leave the clutch pedal depressed for a short while and the gear seems more difficult to engage, if I go from any range to the other quite fast, is easier to go in.
I am thinking about warped clutch or any other thing that would keep the transmission gears turning (shaft, bearing...)

Is there anything I could check externally, lubricate or adjust that could cause this or I really have to split the machine :-(

thanks so much

Answer
  It sounds like you will have no choice but to split the tractor and replace the clutch.  Either the pilot bearing is bad, there is something wrong with the pressure plate, or the disk is warped or broken.  If the pedal is the right height, the clutch doesn't slip, and the pedal has free travel (the amount you can lift the pedal) then there are no external adjustments that will fix it.